K2/100 with SB200 (was K2/100 with LK-500Z)

[w9cf]

Tom Hammond <[hidden email]> wrote:

> Ron:
>
>
>>Is there any reason to use a keying interface between these two? The K2
>>manual says the PA key circuit handles 1 amp at 200v DC. The LK manual
>>doens't say what the exact specs are, but from the schematic it looks
>>like the LK uses 12V for the TX relay. I'm an appliance operator so sure
>>would appreciate advice before I key the amp direct from the rig.
>
>
>Nope, none whatsoever... the MOSFET at the T-R output of the KPA100 is
>more than adequate to key just about any T-R line which offers a POSITIVE
>DC voltage less than about 200VDC and 5A... UNfortunately, it will NOT
>(directly) key some of the older amp T-R lines which offered negative
>voltages.
>
>73,
>
>
>Tom Hammond   N0SS

For negative voltage keying I found that
using the the circuit by K4IQJ from May 1989 QST,
<http://www.arrl.org/members-only/tis/info/pdf/sstrans.pdf> worked well
between a Heathkit SB200 and the K2.  I built it on a Sunday and the
only high voltage P-channel enhancement mode MOSFET available at the
local Fry's electronics was an NTE2381 which is overkill.  I deleted
the zener diode that K4IQJ included to protect the transceiver since the
diode protector in the MOSFET of the K2 is rated to handle the full fault
current from the SB200 (You should verify this yourself before doing
what I did. That is, I believe, [but haven't tried it!] that you can
stupidly connect the SB200 to the K2 directly and the K2 will survive.)

The circuit is simple; I built it into a small plastic box that sits
behind the SB200. The K2 keys (to ground) a 1K ohm resistor connected
to the positive terminal of a 9 volt battery whose negative terminal
connects to the gate of the FET. A 470K ohm resistor connects from
the gate to ground.  The source is grounded, and the drain and ground
connect to the SB200.  K4IQJ included a 15 volt 1 watt zener from the
gate to ground, to clamp the voltage on his rig if the MOSFET failed,
and suggested using an IRF9610, IRF9612, IRF9620, IRF9630 or IRF9632
for the MOSFET.

73 Kevin w9cf

=-------------------------------------------------------------
Kevin Schmidt, [hidden email], http://fermi.la.asu.edu/w9cf
Department of Physics
Arizona State University, Tempe, AZ 85287-1504
[phone] Fax: [phone]
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[srife]

        Or you could just order the softkey module from Harbach Electronics
for the SB-200. It's pretty easy to install, and you would be able to key
the SB-200 with any rig.

Stan Rife
W5EWA
Houston, TX
K2 S/N 4216
 

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Kevin Schmidt
Sent: Wednesday, January 03, 2007 2:21 PM
To: [hidden email]
Subject: [Elecraft] K2/100 with SB200 (was K2/100 with LK-500Z)


Tom Hammond <[hidden email]> wrote:

> Ron:
>
>
>>Is there any reason to use a keying interface between these two? The K2
>>manual says the PA key circuit handles 1 amp at 200v DC. The LK manual
>>doens't say what the exact specs are, but from the schematic it looks
>>like the LK uses 12V for the TX relay. I'm an appliance operator so sure
>>would appreciate advice before I key the amp direct from the rig.
>
>
>Nope, none whatsoever... the MOSFET at the T-R output of the KPA100 is
>more than adequate to key just about any T-R line which offers a POSITIVE
>DC voltage less than about 200VDC and 5A... UNfortunately, it will NOT
>(directly) key some of the older amp T-R lines which offered negative
>voltages.
>
>73,
>
>
>Tom Hammond   N0SS

For negative voltage keying I found that
using the the circuit by K4IQJ from May 1989 QST,
<http://www.arrl.org/members-only/tis/info/pdf/sstrans.pdf> worked well
between a Heathkit SB200 and the K2.  I built it on a Sunday and the
only high voltage P-channel enhancement mode MOSFET available at the
local Fry's electronics was an NTE2381 which is overkill.  I deleted
the zener diode that K4IQJ included to protect the transceiver since the
diode protector in the MOSFET of the K2 is rated to handle the full fault
current from the SB200 (You should verify this yourself before doing
what I did. That is, I believe, [but haven't tried it!] that you can
stupidly connect the SB200 to the K2 directly and the K2 will survive.)

The circuit is simple; I built it into a small plastic box that sits
behind the SB200. The K2 keys (to ground) a 1K ohm resistor connected
to the positive terminal of a 9 volt battery whose negative terminal
connects to the gate of the FET. A 470K ohm resistor connects from
the gate to ground.  The source is grounded, and the drain and ground
connect to the SB200.  K4IQJ included a 15 volt 1 watt zener from the
gate to ground, to clamp the voltage on his rig if the MOSFET failed,
and suggested using an IRF9610, IRF9612, IRF9620, IRF9630 or IRF9632
for the MOSFET.

73 Kevin w9cf

=-------------------------------------------------------------
Kevin Schmidt, [hidden email], http://fermi.la.asu.edu/w9cf
Department of Physics
Arizona State University, Tempe, AZ 85287-1504
[phone] Fax: [phone]
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com